DE10339328A1 - Method for separating trivalent americium from trivalent curium - Google Patents

Abstract

A method is disclosed for separating trivalent americium from trivalent curium, coming from an aqueous solution containing at least these cations, wherein, at an acid concentration of 0.01 mol/l-0.3 mogl/l, the aqueous solution is brought into contact with an organic solvent containing a bis(aryl)dithiophosphinic acid having the formula (4) where R1=phenyl or naphthyl R2=phenyl or naphthyl, and radicals of R1 and R2 substituted by at least one methyl, ethyl, propyl, isopropyl-, cyano, nitro, or halo substituent, and containing a synergist having the formula (5) where X and/or Y and/or Z is R or RO, wherein R is branched or unbranched alkyl.

Description

The The invention relates to a process for the separation of trivalent americium of trivalent curium according to the preamble of claim 1.

The Separation of trivalent actinides, such as americium (Am) or curium (Cm) of the trivalent lanthanides is a long-standing one Problem. Responsible for the difficulty in separating these elements is very similar chemical and physical behavior of the trivalent ions of the Lanthanides and actinides. Especially the very similar Ionic radii contribute to the similar Behavior of these two element groups at. So have been numerous Tried the trivalent ions of actinides and lanthanides with as possible high selectivity and high efficiency.

It Although it is known that extraction agents with soft donor groups, which nitrogen or sulfur as complex-forming structural components included in the liquid-liquid extraction a certain selectivity across from trivalent actinides possess, however, the separations so far only at relatively high pH values, in which the trivalent actinides tend to form precipitates, be made.

To from the publication K.L. Nash, Solvent Extr. Ion Exch. 11 (4), 729-768 (1993) known Talspeak Process is a selective extraction of lanthanides with the help of complexing agents containing the trivalent actinides in solution hold, possible. However, this separation process again takes place at relatively high levels pHs of 3-4 and requires the addition of other salts.

A process provided by the Applicant for the extraction of trivalent actinides from aqueous solutions containing trivalent actinides and trivalent lanthanides allows separation at high acid concentrations of 0.01 to 2 mol / l HNO ₃ ( EP 1 019 552 B1 ). According to this process, such an acidic aqueous solution containing a mixture of trivalent lanthanides and actinides is extracted by means of an organic solvent containing as extractant a bis (aryl) dithiophosphine acid with the addition of a synergist. Due to the low pH or the high acid concentration, this method prevents precipitation of the trivalent actinides and good separation results are already achieved. The characteristic values used to evaluate the separation behavior are the distribution coefficient D and the separation factor SF (Separation Factor). D An (III) = [An (III) org ] / [An (III) w ] (1)

In formula 1 are:
D _{An (III)} = distribution coefficient for a trivalent actinide (dimensionless)
[An (III) _org ] = concentration of the trivalent actinide in the organic phase (mol / l).
[An (III) _w ] = concentration of the trivalent actinide in the aqueous phase (mol / l). D Ln (III) = [Ln (III) org ] / [Ln (III) w ] (2)

In formula 2 are:
D _{Ln (III)} = distribution coefficient for a trivalent lanthanide (dimensionless)
[Ln (III) _org ] = concentration of trivalent lanthanide in the organic phase (mol / l).
[Ln (III) _w ] = concentration of the trivalent lanthanide in the aqueous phase (mol / l). SF = D An (III) / D Ln (III) (3) SF = separation factor (dimensionless)

With a separation factor of SF = 1, no separation is possible.

The according to the method using bis (aryl) dithiophosphinic in strong Acid medium he aimed at separating factors SF between trivalent actinides and trivalent lanthanides are interdependent depending on the synergist 20 to 2000.

• • Etwa ein Drittel der Spaltprodukte sind Lanthaniden.
• • Die Ln(III) besitzen die gleiche Oxidationsstufe III und das chemische Verhalten ist dem der An(III) sehr ähnlich.
• • Einige Lanthaniden haben sehr große Neutroneneinfangquerschnitte und wirken daher als Neutronengifte bei der Transmutation.

Various methods exist for the separation of the trivalent actinides An (III) Am and Cm from the liquid highly active waste, the raffinate of the PUREX process (Madic, C. in the 6 ^th Information Exchange Meeting on Actinide and Fission Product Partitioning and Transmutation, Madrid, Spain, 11-13 December 2000, EUR 19783, 2001, pp. 53-64). In the first step, the anions (III) are co-extracted together with the lanthanides Ln (III) and separated from most of the cleavage products (eg Mo, Zr, Cs, Fe, etc.). The best-known methods include TRUEX, TRPO and the DIAMEX process. All of these processes produce An (III) / Ln (III) fractions, the further separation of which has hitherto caused great problems. So far, there was no extractant that selectively separates An (III) from Ln (III) from strongly acidic solutions. However, if one considers the P & T fuel cycle, in which long-lived actinides are first separated (partitioning, P) and subsequently destroyed by transmutation T, an (III) / Ln (III) separation is essential for the following reasons:

• • About one third of the fission products are lanthanides.
• • The Ln (III) have the same oxidation state III and the chemical behavior is very similar to that of the An (III).
• • Some lanthanides have very large neutron capture cross-sections and therefore act as neutron poisons during transmutation.

In the DIAMEX process, malonic diamides An (III) and Ln (III) are extracted together from the 3 - 4 mol / L HNO ₃ Purex raffinate. After re-extraction with dilute HNO ₃ , a product is obtained which consists predominantly of An (III) and Ln (III) and has an HNO ₃ concentration of about 0.5 mol / L (Madic, C., Hudson Liljenzin, JO; Glatz, JP; Nannicini, R .; Facchini, A., Kolarik, Z. Odoj, R. New Partitioning Techniques for Minor Actinides, European Report, EUR 19149, 2000).

The Applicant has developed a process for actinide lanthanide separation from nitric acid solution (0.5-1.0 mol / L HNO ₃ ). The process is known by the name ALINA process (Actinide (III) lanthanide (III) INtergroup separation in Acidic medium) (Modolo, G. Odoj, R .; Baron, P. The ALINA Process for An (III) / Ln (III) Group Separation from Strong Acidic Medium, Proceedings of Global 99, International Conference on Future Nuclear Systems, Jackson Hole, Wyoming, USA, August 29 - September 3, 1999, American Nuclear Society, Inc.). The extractant was a mixture of aromatic dithiophosphinic acid and trioctylphosphine oxide (TOPO) in tert. Butylbenzene used. Details of the synthesis of the novel extractants, their radiolytic stability, and their suitability for An (III) / Ln (III) separation are given in (Modolo, G., Odoj, R. Synergistic selective extraction of actinides (III), using lanthanides from nitric acid using new aromatic diorganyldithiophosphinic acids and neutral organophosphorous compounds, Solvent Extr. Ion Exch., 1999, 17 (1), pp. 33-53).

The separation of americium and curium, however, is even more difficult than the actinide (III) / lanthanide (III) separation and therefore presents an even greater challenge to process chemistry. This is for the following reasons:
In the trivalent state, americium and curium have very similar chemical properties due to nearly identical internal radii (0.99 and 0.986 angstroms, respectively). In its higher oxidation states (IV, V, VI), americium behaves as a very strong oxidant and therefore the known hydrometallurgical (liquid-liquid extraction) processes (eg PUREX process) are not suitable for the separation of heterovalent actinides due to the instability of all oxidation states except for the trivalent ones.

Therefore No hydrometallurgical process has been described in the literature so far been the americium and curium in the natural oxidation state of Three separate.

It is therefore the object of the invention, a method for separation of americium and curium, which has a particularly high separation factor SF has. The new procedure should works well in already known processes for lanthanide-actinide separation integrate or connect to let.

outgoing The preamble of claim 1, the object is achieved according to the invention, with the features specified in the characterizing part of claim 1.

With the method according to the invention is it now possible Americium (III) and curium (III) with a separation factor of the order of magnitude separate from 10. Allows in addition to the americium (III) / curium (III) separation also an actinide (III) - / (lanthanide) (III) separation.

advantageous Further developments of the invention are specified in the subclaims.

The Figures show exemplary schematic processes.

It shows:

1 : A scheme in which the inventive separation method for americium (III) and curium (III) is connected to a PUREX process.

2 : A scheme for a process in which, starting from a lanthanide solution, both cations americium (III) and curium (III) are separated together, followed by the americium (III) from the curium (III).

According to the method of the invention can which in an aqueous Phase ions of americium (III) and curium (III) separated become. The solution can as well as other lanthanides and / or actinides as well as other components contain.

For this is the aqueous solution containing americium (III) and curium (III) with an organic phase brought into contact, which is an extractant and a synergist.

When organic solvent different systems come into consideration. So pure solvents, as well as solvent mixtures containing at least two solvent components be used.

It can aromatic solvents, especially at room temperature, liquid solvents, such as benzene, toluene, Tert. Butylbenzene, xylene, bis- or tris- (ter-butyl) -benzene, isopropylbenzene, bis- or tris (isopropyl) benzene, alone or in admixture of at least two components are used.

It can also branched and / or unbranched aliphatic solvents, a chain length from, for example, C5 to C14, more generally aliphatic, liquid at room temperature solvent used alone or in a mixture comprising at least two components become. In particular, n-hexane, c.-hexane, heptane, octane, nonane, Decan, undecane, dodecane, kerosene or TPH.

Preferably is used as a solvent a mixture of aromatic and aliphatic solvents used, especially preferably with an aromatic solvent as main component, d. H. > 50%.

When solvent can For example, toluene, hexane, a mixture of toluene and hexane, a Mixture of isooctane and tert. Butylbenzene be called.

The organic solvents is advantageously an aromatic component, such as benzene, toluene, Xylene, tert. Butylbenzene-containing solvent or a purely aromatic Solvent.

In An embodiment of the invention is at least one solvent Component from the group of toluene, xylene, tert-butylbenzene, and bis- or tris (tert-butyl) benzene, Isopropylbenzene, bis- or tris (isopropyl) benzene used. Of the Use of these solvents leads to an additional positive effect: the distribution coefficients of actinides Am (III) and Cm (III) are added improved. The separation factor remains constant at about 10.

The order of effectiveness for the partition coefficient is as follows:
Benzene <toluene <xylene <tert-butylbenzene <n-hexane / toluene (50/50 tab. 4) Bis (isopropyl) benzene, triisopropylbenzene, bis (tert-butyl) benzene, tris (tert. butyl) benzene.

The Extractant in the organic phase is preferred an aromatic dithiophosphinic acid, preferably bis (chlorophenyl) dithiophosphinic acid.

mit R₁ = phenyl- oder naphthyl,
R₂ = phenyl- oder naphthyl,
sowie mit methyl-, ethyl-, propyl-, isopropyl-, cyano-, nitro-, halogenyl- (Cl^–, F^–, Br^–, J^–) substituierten Resten von R₁ und R₂ wobei R₁ und R₂ mit mindestens einer Komponente aus der Gruppe von methyl-, ethyl-, propyl-, isopropyl-, cyano-, nitro-, halogenyl- (Cl^–, F^–, Br^–, J^–) substituiert sein können. Diese Gruppen sind beispielhaft für die Acidität des Extraktionsmittels bis(aryl)dithiophosphin Säure steigernde Substituenten, die zu besonders gutem Extraktionsverhalten führen. Entscheidend ist die Steigerung der Acidität des Extraktionsmittels, auf die genaue Stellung der Substituenten kommt es weniger an.The extraction is generally carried out by means of an organic solvent containing as extractant bis (aryl) dithiophosphinic acid of the general formula (4) R ₂ PS (SH).

with R ₁ = phenyl or naphthyl,
R ₂ = phenyl or naphthyl,
as well as methyl, ethyl, propyl, isopropyl, cyano, nitro, halogenyl- (Cl ^-, F ^-, Br ^-, J ^-) substituted residues of R ₁ and R ₂ wherein R ₁ and R ₂ with at least one component from the group of methyl, ethyl, propyl, isopropyl, cyano, nitro, haloyl (Cl ^- , F ^- , Br ^- , J ^- ) may be substituted. These groups are exemplary of the acidity of the extractant bis (aryl) dithiophosphine acid-enhancing substituents, which lead to particularly good extraction behavior. It is crucial to increase the acidity of the extractant, the exact position of the substituents is less important.

Of the in the organic phase synergist is preferred a trialkyl phosphate (formula (5)) with X, Y, Z = RO, preferably tris (ethylhexyl) phosphate (TEHP) or a trialkylphosphine oxide with X, Y, Z = R, such as Trioctylphosphine oxide (TOPO).

With X and / or Y and / or Z = RO (alkoxy) or R (alkyl), where R is branched and may be unbranched and preferably ranges from C4-C10. in this connection can all radicals X, Y, Z, R or RO. It can, however, each one or two residues of X, Y, Z may be RO or R.

Especially preferably contains the organic phase at least one synergist from the group consisting of trioctyl phosphate (formula (6)), tris (2-ethylhexyl) phosphate (formula (7)) and tris (2-propylpentyl) phosphate (Formula (8)).

With the addition of the synergist of the invention a significant increase of the separation factor SF is effected.

The selectivity in the separation of the americium III from curium III becomes significant increased.

The separation of Am (III) from Cm (III) is carried out at an acid concentration which is dependent on both the material nature and concentration of the extractant, the synergist and the solvent. The conditions must be set so that the distribution coefficient of the Am (III) is greater than 1 and that of the Cm (III) is consequently less than 1. By way of example, Table 4 lists possible acid concentrations for two different solvents for 0.5 mol / L (ClPh) ₂ PSSH + 0.15 mol / L TEHP. The H ⁺ concentrations may be between 0.01-1 mol / L in the separation according to the invention. A range between 0.05 and 0.5 mol / L is preferred. As acids, for example, HCl, H ₂ SO ₄ and ins special ENT ₃ are used because HNO _{3 forms} easily soluble salts.

With this procedure according to the invention can Am (III) of Cm (III) both from a solution containing this alone Components as well as a solution, the extra Ions or cations, such as alkali elements, alkaline earths contains and lanthanides (III) and actinides (IV, V, VI).

In the extraction experiments with dithiophosphinic acids for the Actinide (III) / Ln (III) separation according to the prior art, it has hitherto been assumed that americums have (III) and curium (III) similar behavior and the same extraction properties, ie similar distribution coefficients and thus SF _{Am / Cm} ~ 1. Therefore, curium (III) has not been considered. The results of the extraction experiments with curium (III) surprisingly show a different behavior of both actinide elements. According to the invention, extraction experiments were carried out with synthetic actinide (III) / lanthanide (III) solutions whose composition is shown in Table 1. These actinide (III) / lanthanide (III) solutions are obtained in a DIAMEX process for actinden (III) separation from a PUREX raffinate.

Table 1: Composition of concentrated synthetic actinide (III) / lanthanide (III) solutions from a DIAMEX process, which were traded with Am-241 and Cm-244. The concentrations of the lanthanides (III) correspond to 2.5 or 10 times the expected concentrations. Therefore KF = 2.5 and 10.

The Results of extraction experiments are shown in Tables 2 and 3 shown. One recognizes that the distribution coefficients of Y, Nd, Sm, Eu and Gd are significantly smaller than those of La, Ce and Pr.

Ce is the best extractable lanthanide. Consequently, z. As the Am / Eu separation factor is very high (SF _{Am / Eu} > 1000), but z. For example, the Am / Ce separation factor is only moderate (SF _{Am / Ce} = 25-40). For continuous An (III) / Ln (III) separation, these separation factors would more than be sufficient. But since the distribution coefficient of the Cm is smaller by a factor of 10 than that of the Am, (SF _{Am / Cm} = 10), a separation of the Cm is also possible.

The results in Table 3 illustrate that with this extraction system (ClPh) ₂ PSSH + TEHP even more concentrated An / Ln solutions (KF = 10) can be treated. The comparison with the values in Table 2 shows that although the distribution coefficients of all elements under the same conditions become slightly smaller, the separation factors SF _{Am / Eu} , SF _{Am / Ce} , SF _{Cm / Eu} and SF _{Cm / Ce} increase.

Remarkable are the high Am / Eu and Am / Gd separation factors of more than 2000 achieved here. However, the Am / Ce separation factor is almost 2 orders of magnitude smaller and is 36-40.

Of the Am / Cm separation factor is also around 10. At this point be mentioned that in the literature so far cited no higher separation factor has been. So far, only values below 2 were known.

Table 2:

Extraction of Am (III), Cm (III) and Lanthanides (III) with 0.4 mol / L (ClPh) ₂ PSSH + 0.15 mol / L TEHP in 20 Isooctane / tert. Butylbenzene from a synthetic An (III) / Ln (III) solution.

• Organic phase: 0.4 mol / L (ClPh) ₂ PSSH + 0.15 mol / L TEHP in 20% isooctane / tert. Butylbenzene.
• Aqueous phase: Synthetic An (III) / Ln (III) solution with the composition in Table 1 (KF = 2.5), different HNO ₃ concentrations.

Table 3:

Extraction of Am (III), Cm (III) and Lanthanides (III) with 0.4 mol / L (ClPh) ₂ PSSH + 0.15 mol / L TEHP in 20 Isooctane / tert. Butylbenzene from a synthetic An (III) / Ln (III) solution.

• Organic phase: 0.4 mol / L (ClPh) ₂ PSSH + 0.15 mol / L TEHP in 20% isooctane / tert. Butylbenzene.
• Aqueous phase: Synthetic An (III) / Ln (III) solution having the composition in Table 1 (KF = 10), various HNO ₃ concentrations
  

Table 4 lists some extraction results for Am (III) / Cm (III) separation from nitric acid solution. The results show that the partition coefficients are strongly solvent dependent but the Am / Cm separation factor SF _{Am / Cm is} almost unaffected. The distribution coefficients of Am and Cm (together in solution) were determined by alpha spectroscopy and that of Am in addition to gamma spectroscopy. Alpha spectroscopy has the advantage that both nuclides (here Am-241 and Cm-244) can be measured simultaneously.

Table 4:

Extraction of Am (III) and Cm (III) with 0.5 mol / L (ClPh) ₂ PSSH + 0.15 mol / L TEHP as a function of the solvent.

• Organic phase: 0.5 mol / L (ClPh) ₂ PSSH + 0.15 mol / L tris ethylhxyl phosphate in different solvents.
• Aqueous phase: tracer levels of Am-241 and Cm-244, various HNO ₃ concentrations.

The inventive method can be, as in 1 represented, to known separation methods shut down. In 1 is shown on the basis of a reprocessing of spent fuel for the separation of uranium and plutonium (Neptunium), as well as subsequent separation of the trivalent actinides americium and curium from the HAW (PUREX raffinate), as a separation process can look like:
The spent fuel elements can be fed to a PUREX process in which U, Pu and Np are separated. The highly active liquid waste (HAW) is fed to a separation of actinides (III) and lanthanides (III).

mit R1 = phenyl- oder naphthyl,
R₂ = phenyl- oder naphthyl,
sowie mit methyl-, ethyl-, propyl-, isopropyl-, cyano-, nitro-, halogenyl- (Cl^–, F^–, Br^–, J^–) substituierten Resten von R₁ und R₂ wobei R₁ und R₂ mit mindestens einer Komponente aus der Gruppe von methyl-, ethyl-, propyl-, isopropyl-, cyano-, nitro-, halogenyl- (Cl^–, F^–, Br^–, J^–) substituiert sein können. Diese Gruppen sind beispielhaft für die Acidität des Extraktionsmittels bis(aryl)dithiophosphinsäure steigernde Substituenten, die zu besonders gutem Extraktionsverhalten führen. Entscheidend ist die Steigerung der Acidität des Extraktionsmittels, auf die genaue Stellung der Substituenten kommt es weniger an.The separated actinides (III) and lanthanides (III) are subjected to a selective actinide (III) separation, which can be carried out, for example, by the process according to European patent 1019552. According to the process of European patent 1019552, trivalent ions of lanthanides (cerium), (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pr), samarium (Sm), europium (Eu) are exemplified in an aqueous phase. , Gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), luthenium (Lu), and lanthanum (La) and yttrium (Y ) or at least one component from this group and ions of trivalent actinides such as americium (Am) and / or curium (Cm). The aqueous phase has a low pH, which corresponds to a H ⁺ concentration of a strong acid of 0.01 to 2 mol / l. As acids, HCl, H ₂ SO ₄ and in particular HNO ₃ can be used, since HNO _{3 forms} easily soluble salts. The extraction is carried out by means of an organic solvent which contains as extractant bis (aryl) dithiophosphinic acid of the general formula (4) R ₂ PS (SH).

with R1 = phenyl or naphthyl,
R ₂ = phenyl or naphthyl,
as well as methyl, ethyl, propyl, isopropyl, cyano, nitro, halogenyl- (Cl ^-, F ^-, Br ^-, J ^-) substituted residues of R ₁ and R ₂ wherein R ₁ and R ₂ with at least one component from the group of methyl, ethyl, propyl, isopropyl, cyano, nitro, haloyl (Cl ^- , F ^- , Br ^- , J ^- ) may be substituted. These groups are exemplary of the acidity of the extractant bis (aryl) dithiophosphinic acid increasing substituents, which lead to particularly good extraction behavior. It is crucial to increase the acidity of the extractant, the exact position of the substituents is less important.

exemplary contains the organic phase at least one synergist from the group consisting of trioctyl phosphate (formula (6)), tris (2-ethylhexyl) phosphate (Formula (7)) and tris (2-propylpentyl) phosphate (Formula (8)).

It can but also the synergists of the general formula (5) used become.

With the addition of synergists will cause a significant increase in the separation factor SF causes. The selectivity in the separation of the actinides from the lanthanides becomes significant increased.

The organic solvents is advantageously an aromatic component, such as benzene-containing solvent or a purely aromatic solvent.

In a particularly advantageous embodiment of the invention is at least one component from the group of toluene, xylene, tert-butylbenzene, and bis- or tris- (tert-butyl) benzene, isopropylbenzene, bis- or tris- (isopropyl ) benzene used. The use of these solvents leads to two additional positive effects: On the one hand, the selectivity of the An ³⁺ extraction is further increased the distribution coefficient D _{An (III) is} additionally improved.

The order of effectiveness for the separation factor SF and the distribution coefficient behave as follows:
Benzene <toluene <xylene <tert-butylbenzene <bis (isopropyl) benzene, tri-isopropylbenzene, bis (tert-butyl) benzene, tris (t-butyl) benzene.

in the Connection is the separation of Americium III and Curium III with the method according to the invention.

A process control according to the inventive method is exemplified in 2 specified.

2 shows a Der LUCA process for actinide (III) / lanthanide (III) separation followed by americium / curium separation.

In this illustration, the actinides (III) are prepared from an aqueous solution containing an americium (III) and curium (III) and lanthanides (III) with 0.1 mol / L HNO ₃ with an extraction agent consisting of 0.4 mol / L (ClPh) ₂ PSSH and 0.15 mol / L tris ethylhexyl phosphate, extracted in an organic solvent. Curium III is then reextracted with a 0.3 mol / L HNO ₃ solution. Thereafter, the re-extraction of americium (III) with 1.0 mol / L HNO ₃ .

• 1. Selektive Extraktion von Am und Cm. Die Lanthaniden Ln(III) hier Y, La, Ce, Pr, Nd, Sm Eu und Gd verbleiben im Raffinat (in Abbildung = Ln(III)).
• 2. Selektives Strippen von Cm(III)
• 3. Strippen von Am(III).

The flowchart looks like this:

• 1. Selective extraction of Am and Cm. The lanthanides Ln (III) here Y, La, Ce, Pr, Nd, Sm Eu and Gd remain in the raffinate (in Figure = Ln (III)).
• 2. Selective stripping of Cm (III)
• 3. stripping of Am (III).

Claims (9)

A process for the separation of trivalent americium from trivalent curium from an aqueous solution containing at least these cations, characterized in that the aqueous solution at an acid concentration of 0.01 mol / l - 1 mol / l with an organic solvent containing a bis (aryl) dithiophosphinic acid of general formula (3)

with R ₁ = phenyl or naphthyl, R ₂ = phenyl or naphthyl, and with methyl, ethyl, propyl, isopropyl, cyano, nitro, halogenyl (Cl ^- , F ^- , Br ^- , J ^- ) substituted radicals of R ₁ and R ₂ wherein R ₁ and R ₂ with at least one component from the group of methyl, ethyl, propyl, isopropyl, cyano, nitro, haloyl (Cl ^- , F ^-, , Br ^- , J ^- ) and a synergist of the general formula (5)

with X and / or Y and / or Z = RO (= alkoxy) or R (= alkyl), where R can be branched and / or unbranched in contact. Method according to claim 1, characterized in that that the organic solvent an aromatic solvent, an aliphatic solvent or a mixture thereof. The method of claim 2; characterized, that the aromatic solvent at least one component from the group consisting of benzene, Toluene, tert. Butylbenzene, xylene, bis- or tris- (ter.-butyl) -benzene, isopropylbenzene, bis- or tris (isopropyl) benzene. Method according to claim 2, characterized in that that the aliphatic solvent at least one component from the group of branched or unbranched aliphatic solvent a chain length from C5 to C14. Method according to claim 2 or 4, characterized that the aliphatic solvent at least one component from the group consisting of n-hexane, c-hexane, heptane, octane, nonane, decane, undecane, dodecane, kerosene or TPH is. Method according to one of claims 2 to 5, characterized that the aromatic solvent is used as the main component. Method according to one of claims 1 to 6, characterized that it is followed by a lanthanide actinide separation process is. Method according to claim 7, characterized in that that the lanthanide actinide separation process is a Talspeak, TRUEX, TRPO or Diamex process. A method according to claim 7, characterized in that the lanthanide actinide separation method is a process in which the actinides are prepared from an aqueous solution by means of a solvent containing a bis (aryl) dithiophosphinic acid of the general formula (4)

with R ₁ = phenyl or naphthyl, R ₂ = phenyl or naphthyl, and with methyl, ethyl, propyl, isopropyl, cyano, nitro, halogenyl (Cl ^- , F ^- , Br ^- , J ^- ) substituted radicals of R ₁ and R ₂ wherein R ₁ and R ₂ with at least one component from the group of methyl, ethyl, propyl, isopropyl, cyano, nitro, haloyl (Cl ^- , F ^-, , Br ^- , J ^- ) and a synergist of the general formula (5)

with X and / or Y and / or Z = RO (= alkoxy) and / or R (= alkyl), where R can be branched and / or unbranched, is extracted.